1. Field of the Invention
This invention relates to fluid handling processes and apparatus. More particularly, this invention relates to new methods and apparatus for distributing the flow of fluid from a spray head.
2. Description of the Related Art
Spray heads are commercially available in numerous designs and configurations for use in showers, faucets, whirlpools, sprinklers, and industrial processes. For example, in shower applications, one may encounter spray heads being used as either showerheads or body sprays. As a showerhead, the spray is placed at a height that is front of or slightly higher than a user's head and it, at typical flowrates of 2.0–2.5 gpm, serves as the primary or only means of supplying liquid to the user. As a body spray, one or more rows of such sprays are typically placed in a shower's front or side walls. At typical flowrates of 1.5–2.5 gpm, body sprays typically serve as ancillary sprays which have smaller target areas than showerheads.
While many spray heads are designed and sold for their decorative styling, there are a great number of different showerhead mechanisms which are intended to improve or change one or more characteristic of the water spray pattern. Any particular spray pattern may be described by the definable characteristics of the spray pattern, including the volume flow rate of the spray, the spray's area of coverage, the spatial distribution of spray droplets in a plane perpendicular to the direction of flow of the spray, the average spray droplet velocities, the average size of the spray droplets, and the frequency of the spray droplets impacting on an obstacle in the path of the spray. Furthermore, these characteristics may be used to adapt a spray pattern for specific service purposes, including a pulsating jet stream for massaging of muscles, a more uniform soothing spray to provide maximum wetting.
Stationary spray heads with fixed jets are the simplest of all spray heads, consisting essentially of a water chamber and one or more jets directed to produce a constant pattern. Stationary spray heads with adjustable jets are typically of a similar construction, except that it is possible to make some adjustment of the jet opening size and/or the number of jets utilized. However, these types of jets provide a straight often piercing directed flow of water.
These stationary spray heads cause water to flow through its apertures and contact essentially the same points on a user's body in a repetitive fashion. Therefore, the user feels a stream of water continuously on the same area and, particularly at high pressures or flow rates, the user may sense that the water is drilling into the body, thus diminishing the positive effect derived from such a spray head. In order to reduce this undesirable feeling, various attempts have been made to provide spray heads that vary or enlarge the areas being impacted by the sprays.
Examples of such spray heads seeking broader patterns of spray droplet distribution include the showerheads disclosed in U.S. Pat. No. 3,691,584 (Drew et al.), U.S. Pat. No. 4,944,457 (Brewer), U.S. Pat. No. 5,577,664 (Heitzman) and U.S. Pat. No. 6,360,965 (Clearman).
U.S. Pat. No. 4,944,457 discloses an oscillating spray head that uses an impeller wheel mounted to a gear box assembly which produces an oscillating movement of the nozzle. See FIG. 1.
Similarly, U.S. Pat. No. 5,577,664 discloses a spray head having a rotary valve member driven by a turbine wheel and gear reducer for cycling the flow rate through the housing between high and low flow rates, causing the spray droplets to be distributed over broader areas. Additionally, the turbine wheels of this spray head may be used to control the frequency of the spray droplets impacting on an obstacle in the path of the spray, thereby using this phenomena to cause the flow from the spray to exhibit pulsating features for massaging purposes. See FIGS. 2A–2B. For an example of another type of massaging shower head, see U.S. Pat. No. 5,467,927 (Lee).
All of these spray heads require extremely complex mechanical structures in order to accomplish the desired broader distribution of a spray's droplets. Consequently, these mechanisms are prone to failure due to wear on various parts and mineral deposits throughout the structure.
U.S. Pat. No. 3,691,584 also discloses a spray head that attempts to efficiently distribute its droplets over a wider area. See FIG. 3. It utilizes a nozzle mounted on a stem that rotates and pivots under forces placed on it by water entering through radially disposed slots into a chamber around a stem. Although this spray head is simpler than those of Brewer, Heitzman or Lee, it still includes a large number of piece requiring precise dimensions and numerous connections between pieces. Furthermore, the Drew spray head relies upon small openings for water passageways and is subject to mineral buildup and plugging with particles.
U.S. Pat. No. 6,360,965 discloses a spray head, see FIG. 4, that distributes its droplets over a wider area by utilizing a means for wobbling the nozzle assembly of such a spray head. FIG. 5 shows the reported typical spatial distribution of spray droplets from such a spray head. Meanwhile, FIGS. 6A–6D which are reproduced from U.S. Pat. No. 6,360,964 are reportedly graphical representations of the uniformity of the spray patterns from four shower heads, including three commercially available shower heads and a shower head made in accordance with FIG. 5. The droplets were collected at a specified distance from the spray head in a row of glass tubes. The graphs represent a side view of the liquid collected in the tubes. The spray head of FIG. 5 is seen to provide the most uniform distribution of liquid across the width of the spray pattern.
In addition to using various forms of mechanical parts in such spray heads to vary the flow from them, it is also well known in the art that an assortment of fluid oscillating devices which have no moving parts in spray heads can be used to provide a wide range of fluid droplet distributions. Such fluid oscillating devices are known as fluidic oscillators and employ especially constructed fluid circuits or pathways to cyclically deflect the flows from spray nozzles.
FIG. 7 from U.S. Pat. No. 4,052,002 (Stouffer & Bray) and FIGS. 8A–8B from U.S. Pat. No. 4,151,955 (Stouffer) demonstrate some of the flow patterns that can be achieved with various types of fluidic oscillators.
FIG. 7 shows what can be considered to be the essentially two-dimensional, planar flow pattern (i.e., in the x-y plane of the oscillator) of a very small diameter, essentially round jet of liquid that issues from the oscillator and then breaks into droplets which are distributed transversely (i.e., in the y-direction) to the jet's generally x-direction of flow. FIG. 8A shows a similar flow pattern. However, this particular flow pattern owes its existence in large part to the specific geometry of this oscillator, especially the distance between this oscillator's island and its outlet.
When this distance is not sufficiently large, the flow from this oscillator is seen to take on a fully three dimensional flow pattern. See FIG. 8B. In this instance, the flow from the oscillator no longer resembles that of a constant round jet whose droplets are distributed in the x-y plane. Instead, the shape of the flow exiting the oscillator is seen to change with time. Somewhat surprisingly, it is seen to have a significant component in the z-plane, which is normal to the x-y plane of the oscillator. The shape of the flow at the oscillator's outlet can be described as that of a thin sheet of fluid in the z-x plane. However, the height (i.e., in the z-direction) of this sheet varies as a function of time and is seen to cycle between instances in which it has considerable height and other instances in which it contracts until it's height is such that it more closely resembles that of an approximate round jet.
FIG. 8B attempts to illustrate this three-dimensional flow pattern. The varying height sheet of liquid (i.e., h(t)) from the oscillator is seen to be swept back and forth in the x-y plane. The points where the sheet shrinks down to its minimum height are denoted by the letters M in FIG. 8B. The resulting wetting pattern that is produced on a downstream target surface is diamond-shaped. The diamond width W is dependent upon the sweep angle in the x-y plane of the oscillator; the diamond height H depends upon the maximum height of the sheet.
Even when the flows from fluidic oscillators are essentially two-dimensional, as in FIGS. 7 and 8A, they can differ in another important aspect or characteristic as it relates to their suitability for use in various spray head or showerhead applications. This characteristic is the frequency with which the flows are being swept from side-to-side.
The fluidic oscillator of FIG. 7 typically can be shaped so that its oscillating frequency is in the range of that which can be sensed by human's tactile sensations (< about 60 Hertz or cycles per second (cps)); thus this oscillator could be used to provide one with a massaging sensation as the droplets impact on one's skin. Meanwhile, the oscillator of FIG. 8A, for a wide range of its applicable geometries, tends to exhibit three-dimensional flow patterns and oscillating frequencies that are considerably above 60 hertz, which results in the pulsating nature of such a flow not be discerned when it impacts on one's skin.
FIG. 9 from U.S. Pat. No. 4,151,955 discloses a showerhead that employs a fluidic oscillator that essentially combines two fluidic circuits of the types shown in FIGS. 7 and 8A. For this application, the circuit of FIG. 8A is configured so as to yield a three-dimensional flow pattern.
Despite much prior art relating to spray heads and showerheads or body spray devices, there still exists a need for further technological improvements in this area. For example, to get a uniform distribution of droplets over a relatively large surface area (e.g., a 400 cm2 area at a distance of 30 cm from the spray's exit), large diameter, so called rain-maker shower heads are often used.
However, such rain-maker shower heads usually have many fine diameter orifices that can become clogged and their resulting sprays are often characterized as: (a) having low velocity (e.g., < or ˜3 m/sec), small diameter (e.g., <1.5 mm) droplets which are inadequate for some bathing purposes (e.g., washing one's hair) if such shower heads are operated within governmentally imposed flow rates (e.g., 2.5 gpm), and (b) being thermally inefficient because of the comparatively higher heat losses experienced by small diameter, as opposed to large diameter, droplets in such sprays. Unfortunately, there are no individual spray heads in today's marketplace that can provide uniform coverage of large surface areas with large diameter (e.g., > or ˜2 mm), high velocity (e.g., > or ˜4 m/sec) droplets.
Improved spray heads continue to be needed that can provide controllable sprays of droplets that prove to be more efficient and effective in assorted applications, such as by providing better performance or greater tactile pleasures in many showerhead and body spray applications.